Safety plate



May 17, 1949. I F. E. KOHLER 2,470,43

SAFETY PLATE Filed March 5', 1947 INVENTOE. FfifflEE/(K E KOA L 5e M/w/W Patented May 17, 1949 UNITED STATES ATENT OFFICE SAFETY PLATE Frederick E. Kohler, Berkeley, Calif. Application March 3, 1947, Serial No. 732,107

4 Claims. 1

This invention relates to improvements in clamping devices, and is particularly concerned with an improved safety plate adapted to be mounted between a supporting structure and one of the jaws of a clamp. In one embodiment, it takes the form of a metallic plate which is placed against a structural part of a boat, such as the stern transom, for holding in place a clamp used. to attach an outboard motor to the boat. The safety plate may, however, be used for securing other clamps to supports.

An outboard motor is usually attached to the stern transom of a boat by means of one or more screw clamps or cam actuated clamps. The vibrations of the motor and the lateral and upward thrusts on the clamp occasioned by the operation of the craft frequentl result in slipping between the supporting clamp and the transom and the frictional engagement of the clamps is usually insufficient to prevent creeping of the clamp along the transom. As a consequence outboard motors frequently become detached from the boat and drop into the water.

While such outboard motors can be firmly secured to boats by means of bolts and clamping plates bolted to the transom, such expedients are not commonly in use because their application is time-consuming and because users of outboard motors frequently attach their motors to hired boats which are not provided with the requisite fixtures, the clamping arrangements being, moreover, not of identical design.

It is the principal object of the present invention to provide an improved safety plate which will reduce the danger of relative motion between a supporting structure and a compression clamp.

It is a further object to provide an improved safety plate which is simple and efficient and which may either be permanently secured to a boat or other support, or may be employed without screwing, bolting, or otherwise fixing it to the support, other than by the action of the compression clamp.

Still another object is to provide a clamping arrangement wherein vibrations of the supported or supporting structure will automatically tighten the clamp.

A more specific object is to provide an improved arrangement for attaching an outboard motor to a supporting part of a boat, such as the stern transom, which will minimize the danger of loss of the motor by slipping of the clamp along its supportin structure.

With these and other objects in view, which will be in part obvious and in part pointed out in the course of the following description of the elements and applications of principles constitutin the invention, reference is made to the accompanying drawings, forming a part of this specification and illustrating two specific embodiments of the invention, wherein:

Fig. l is a longitudinal cross-sectional view of a boat, parts being shown in side elevation, illustrating one mode of applying the invention;

Fig. 2 is a cabinet projection of the safety plate shown in Fig. 1;

Fig. 3 is an elevation view of a modified form of safety plate; and

Fig. 4 is an end view of the safety plate shown in Figs. 1 and 2.

Briefly, the novel element of my clamping arrangement comprises a safety plate the inclined faces of which are inclined slightly one to another so as to impart to the plate a trapezoidal cross-section. This plate is placed against the surface of the support with its thicker edge toward the free edge of the support. The face of the safety plate in contact with the support, hereinafter referred to as the inner face, is irregular or roughened, being preferably provided with serrations, for preventing sliding movement with respect to the support. When the support is made of yieldable material, such as wood or plastic, or a metal which is softer than that of which the safety plate is constructed, the serrations indent the surface of the support slightly to prevent slipping. The inner face of the plate may, of course, also or instead engage a complementary serrated yieldable or rigid surface on the support. The other face of the safety plate, hereinafter designated the outer face, is relatively smoother, 1. e., it may be quite smooth or slightly rough; it is engaged by one of the jaws of the clamp, which may be either fixed or movable. In the embodiment shown in the drawings the movable jaw of the clamp engaged the safety plate, while the fixed jaw engaged the remote surface of the support. The safety plate is so positioned that the clamp jaw engages the plate at or near the thinnest part of the plate. The plate has a flange or other means, such as a projection, extending from the outer face to engage the side of the engaging clamp jaw to prevent this jaw from sliding away from the thicker edge.

With the arrangement described above, the clamp is firmly secured to its support notwithstanding vibrations imposed either on the support or on the clamp as would be caused, for example, by the operation of an outboard motor carried by the clamp. Vibrations which urge the clamp away from the free edge of the support cause the enaging jaw to bear against the Plate flange or other positive stop or projection thereon; when such movement is not prevented by engagement of the clamp arms with the free edge of the support, this pushes the safety plate away from the free edge of the support. Vibrations which urge the clamp toward the free edge of the support, 1. e toward disengagement therewith, cause the engaging clamp jaw to slide up the inclined outer face of the safety plate, thereby further tightening the rough, inner face against the support. It was found in practice that this action takes place with a plate ef the design described herein in preference to an upward movement of the safety plate.

The invention will be better understood by ref-- erence to the drawings illustrating certain specific modes of applications. Figs. 1, 2 and 4 should be taken together; theyshow the invention applied .to a boat having a bottom 5 *and'a stern transom 6. An outboardmotor, indicated generallyat 1, having. a. propeller .8, is attached to the stern transom by means of a clamp having a'movable jaw in'the form of a screw 9. The motor has a hinged connection with the clamp at 10. The fixed jaw :l lhofthe clamp engages the outer face of the transom.

In this embodimentthe stern transom. is the support and .its upper edge is the freeedge. The safety plate I2 is placed against the inner surface of the transom and clampedthereto by the movable jaw 9. The inner face of the safety plate has horizontalserrati-ons l3,'preferably with sharp ridges. The outer face I4 is inclined with respect to the inner face, as .s'hown'more-particularly in Fig. .4. A suitable-incline for acast plate made of-aluminum is 5%, i. -e., the-outer face slopes away from the inner-face atthearate of one -inch= for twenty :inchesin height of. the plate. 'Imay, however; also-use other slopes, e; vg., 3%to and slopes falling outside oil-this range may, under certain conditions, be used When the slope is too great and/or the outer face is too rough: the vibrations tend to shift the safety plate toward the free edge of the support insteadwof causing the jaw to slide up the incline to wedge the safety plate more tightly against the support.

Afiange l5extends along the thinner edge of the plate, i. e., along the lower edge in the embodiment shown. Asimi lar flange l 6 may be pro videdat the thicker edge but may, if desired, be omitted. The ends of the serrations are pref.- erably provided with bevelled ends H to assist in restraining the plate against horizontal motion, but a bevelled construction is optional. Sim.- ilarly, holes l8 maybe provided optionally for mounting the safety plate on the support by means of fiat head wood'screws, not shown. Such an attachment would be used-merely as a convenience andis not essential to the functioning of the safety plate, whichoperates satisfactorily without being secured to the support by anyforceother than the force of the clamp.

Iii-using the device thesafety plate is placed as shown in Fig. 1 and the clamp is attached with the head of themovable jaw9 in enga ment with thelower'fla-nge 15,. The clam-1: is tightened .and will then remainin position notwithstanding considerable vibration.

iii

for preventing lateral as well as vertical movement of the plate with respect to its support. This plate may optionally be provided with screw Its outer face, not shown, is constructed at an incline and with flanges, like the face i4 ofthe-plate shown in Figs. 1 to 3. The mode of use of this modified plate is the same as previously described.

The safety plate may be constructed of any suitable material, such .as stainless steel, :bmnze or aluminum, .andimay be-machinedxorvcast.

While the safety plate has been shown :as applied to the mounting of an outboardmotor toa boat, it is evident that the invention is not restricted to such use, vbutmay be used tossecure other clamps .to-supports, particularly :where such clamp is subjected to vibrations.

I claim as my invention:

1. A'safety plate for clamps having two. faces inclined one with respect :to the other. one 'face being rough and the-other-smoother, and means on the smoother face extending: substantially along a line of constant thickness of said plate for engaging a clamp'ag-ainst sliding movement past the thinner :edge of the plate.

2. A safety plate for clamps having two faces inclined one with respect to the other, serrations on one face, the other face being adapted'fto engage the jaw of aclamp so as to permit Slide ing motion of said jaw 'forat least a portion 10f the plate in the direction'toward .the thicker edge, and means near the thinner edge of'the plate extending substantially-across the plate at a "line of constant thickness of said plate and for preventing sliding motionnof said jaw past thethinner edge of the'plate.

3. The plate according to claim 2' in which the ends of theserrations are bevelled.

4. A safety plate for clamps having two faces inclined one with respect to the other and ser. rations on one face, the other face being smoother than the face with serrations, and a pair of flanges extending outwardly from-the smoother face, one flange being along the thinner edge and-the other alongthe thicker edgexof the plate.

FREDERICK E. KOHLER.

REFERENCES CITED The following references are of record lnthe file of this patent:

STATES PATENTS Number Name Date 1,298,970 Lampert Apr. 1, 1919 1,663,260 Mould Mar. 20,1928 2,277,939 Thalham-mer Mar. 31, 1942 2,379,256 Schleisner June26, 1945 

